Related to calcium metabolism, which of the following does not occur during pregnancy
**Core Concept**
During pregnancy, calcium metabolism undergoes significant changes to meet the increased demand for calcium by the fetus. This is primarily due to the high rate of fetal growth and development. The maternal body adapts to this increased demand by increasing intestinal absorption of calcium and mobilizing calcium from bone.
**Why the Correct Answer is Right**
The correct answer is related to the fact that the maternal kidney excretes more calcium in the urine during pregnancy. This is due to the increased levels of parathyroid hormone-related protein (PTHrP) produced by the placenta, which suppresses the action of parathyroid hormone (PTH) and leads to decreased renal reabsorption of calcium. As a result, the maternal kidney excretes more calcium in the urine, which is excreted in the urine and not reabsorbed.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because it is not a known effect of pregnancy on calcium metabolism. However, during pregnancy, the maternal body does increase intestinal absorption of calcium and mobilize calcium from bone to meet the increased demand for calcium by the fetus.
* **Option B:** This option is incorrect because it is a known effect of pregnancy on calcium metabolism. The maternal kidney does excrete more calcium in the urine during pregnancy due to the increased levels of PTHrP produced by the placenta.
* **Option C:** This option is incorrect because it is a known effect of pregnancy on calcium metabolism. The maternal body does increase intestinal absorption of calcium and mobilize calcium from bone to meet the increased demand for calcium by the fetus.
**Clinical Pearl / High-Yield Fact**
A key clinical point to remember is that pregnant women with a history of osteoporosis or other bone diseases may be at increased risk of developing bone disease during pregnancy due to the increased demand for calcium by the fetus.
**Correct Answer: B. The maternal kidney excretes more calcium in the urine during pregnancy.**